Conventional solar radiation collectors used to heat a liquid medium include collector plates which are provided with tubing through which the liquid medium passes. This type of collector is expensive to construct and easy to damage as the tubes ae often broken or loosened from the surface of the plate due to temperature variations and thermal expansion. Further, with existing collector plates a liquid medium does not flow over and cover essentially all of the rear face of the plate. Instead, the liquid medium flowing through the tubing is in contact with only discrete portions of the plate. This means that a large amount of heat energy collected by the plate is not directly absorbed by the liquid medium because much of the heat energy must be conducted across the plate and through the tubing before reaching the liquid medium. This results in an inefficient operation of the collector.
The free liquid medium flow rates over the rear face of other types of conventional collector plates is also limited. The liquid medium flows down the rear face of the plate very quickly in samll streams and cannot be effectively heated at high flow rates because the heat energy must be conducted across the plate in order to heat the small streams.
It is therefore an object of the present invention to overcome the above problems by providing a solar radiation collector plate which collects heat energy to heat a liquid medium and which has a rear face adapted to cause a liquid medium to flow over in direct thermal contact with and to cover essentially all of the rear face at a variety of flow rates.
It is another object of the invention to provide a solar radiation collector plate for use in a solar radiation collector which collects heat energy to heat a liquid medium which is highly efficient, inexpensive to construct and more durable.
It is a further object of the invention to provide a solar radiation collector in which collected heated energy is efficiently transferred to and absorbed by a liquid medium.
It is yet another object of the invention to provide a solar radiation collector plate from which a liquid medium absorbs substantial amounts of heat energy while flowing thereover at a relatively higher flow rates.